A burst water pipe in Wellington CBD has now been fixed but Wellington Water says it can't say a similar event won't happen again.
About 100 properties around Waring Taylor Street, Queens Wharf and Hunter Street were left without running water for hours yesterday.
Water tankers were set up in the CBD, with residents and business having to bring their own containers.
Wellington Water's head of network operations and engineering Tim Harty told Morning Report the water pipe burst during planned maintenance on Wednesday night.
"We were trying to work through the night to minimise disruption and we had an unexpected failure of a pipe just upstream where we were working," he said.
Everything was now back to full service, he said.
But Harty could not promise there would not be more pipe bursts in the future.
"We can never say that this will never happen again.
"The pipes in the network in the CBD particularly, are complex and are older and we're renewing them as fast and as quick as we can," he said.
"We'll always see failures in this type of network ... it's an ageing network and we'll continue to have these sorts of challenges."
But Harty said Wellington Water was carrying out proactive work to minimise the impacts of the issues as much as possible.
He advised those affected to run their taps for about five minutes as the water becomes clear, before using it.